There was a time when the Celtics’ acquisition of Xavier Tillman looked like another stroke of genius from Brad Stevens. It shored up the big man depth ahead of the championship run, and at just 25 years old, he seemed perfectly capable of becoming a long-term quality backup.
Tillman dealt with knee swelling during his first season in Boston and, despite a post-title surgery that was supposed to address it, he continued to appear on the injury report with various knee issues. As a result, his playing time was limited and his role was nonexistent.
In Year One, Tillman appeared in 20 regular season games, playing a total of 274 minutes. In Year Two, he logged just 231 minutes across 33 games. His number was rarely called, and he was leapfrogged by Neemias Queta, despite being previously trusted in pivotal playoff moments.
With Boston’s unique roster turnover, the door is open again for Tillman to earn a spot in the rotation. His position in the depth chart arguably hasn’t changed much, but the talent ahead of him is considerably weaker. That reality gives him a clearer path than he’s had since arriving in Boston.
Tillman’s appeal has always been on the defensive end. At his best, he can credibly guard multiple positions. Holding his own on switches and being able to handle physicality made him a formidable Al Horford understudy. Historically, many advanced metrics rated him extremely well on that end too, including Dunks & Threes’ defensive EPM, which placed him in the 99th percentile in ‘23–‘24.
The inconsistencies of his Celtics tenure make it easy to forget, but he’s not far removed from starting in the playoffs against the Lakers — a series where he matched up with Anthony Davis and didn’t blink.
Following the departures of Horford, Luke Kornet, and Kristaps Porzingis — along with Jayson Tatum’s injury — the Celtics could really use an injection of defense into the frontcourt. Tillman has the ability to fill some gaps there. He’s not the towering rim protector type like Kornet and Porzingis, but resembles Horford in some ways with intelligent team defense and switchability.
The numbers also say he’s been one of the league’s best defensive bigs at forcing turnovers. This possession is a nice snapshot of strong positioning and quick hands leading to an easy swipe:
The problem lies in the fact that in the modern NBA, Tillman has an offensive skill set that isn’t valued particularly highly. He is an undersized five, and he’s neither a spacer on the perimeter nor an above-the-rim finisher. He’s flashed passing instincts, but without a perimeter shot or dynamic ball-handling, his offensive game can feel stuck between roles.
His best chance to carve out a role is by proving that his jump shot is real, and something defenses need to respect. For his career, he’s a 25% shooter from three on low volume. If he can climb anywhere near league average, there’s a world where ancillary attributes like strength and short-roll playmaking could get him to the point where he’s adding value, or at least creeping up from a negative.
Offseason workout videos are an unreliable source of excitement, but Tillman looks to be in very good shape, and it’s clear that his three-point shot continues to be a major point of emphasis.
In the moments Tillman was called on last year, he was often playing next to another big. The results were generally underwhelming, but having a reliable jumper in his arsenal could make those lineups a much smoother fit.
It’s wishful thinking to anticipate a mid-career evolution for any player, but this feels like a crossroads year for Tillman — and reinventing himself a bit might be the best way to prolong his NBA career.
He’s young enough to still carve out a niche, but after two seasons on the fringe of the rotation, he’ll need to prove his durability and value quickly. Otherwise, the Celtics may look elsewhere for backup big man minutes.
If the knees hold up and the jumper comes around, he could finally deliver on the promise that made Stevens trade for him. If not, his Celtics tenure — and perhaps his place in the league — may come to a quiet end.
